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Plant, Cell & Env: A novel Arabidopsis-oomycete pathosystem; differential interactions with Phytophthora capsici reveal a role for camalexin, indole glucosinolates and salicylic acid in defense (2012)

Plant, Cell & Env: A novel Arabidopsis-oomycete pathosystem; differential interactions with Phytophthora capsici reveal a role for camalexin, indole glucosinolates and salicylic acid in defense (2012) | Plants and Microbes | Scoop.it
Phytophthora capsici causes devastating diseases on a broad range of plant species. To better understand the interaction with its host plants, knowledge obtained from a model pathosystem can be instrumental. Here we describe the interaction between P.capsici and Arabidopsis and the exploitation of this novel pathosystem to assign metabolic pathways involved in defense against P.capsici. Inoculation assays on Arabidopsis accessions with different P.capsici isolates revealed interaction specificity among accession-isolate combinations. In a compatible interaction, appressorium-mediated penetration was followed by the formation of invasive hyphae, haustoria and sporangia in leaves and roots. In contrast, in an incompatible interaction, P.capsici infection elicited callose deposition, accumulation of active oxygen species and cell death, resulting in early pathogen encasement in leaves. Moreover, Arabidopsis mutants with defects in salicylic acid signaling, camalexin or indole glucosinolates biosynthesis pathways displayed severely compromised resistance to P.capsici. It is anticipated that this model pathosystem will facilitate the genetic dissection of complex traits responsible for resistance against P.capsici.
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YouTube: CEND’s 10th Annual Symposium– “Confronting Persistent Epidemics”, January 12, 2018

YouTube: CEND’s 10th Annual Symposium– “Confronting Persistent Epidemics”, January 12, 2018 | Plants and Microbes | Scoop.it

10th Annual @CENDUCBerkeley Symposium: Confronting Persistent Epidemics. Blast Diseases Session.

 

Barbara Valent: Follow the Effectors: Understanding Ancient and Emerging Blast Diseases on Rice and Wheat https://youtu.be/QoIPSPaEPzY

 

Nick Talbot: Combating the Cereal Killer: Investigating the Biology of Rice Blast Disease https://youtu.be/9AA7akJ21ZI

 

Sophien Kamoun: BLASTOFF - Keeping Up With A Cereal Killer https://youtu.be/FCS5y_qX8n0

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PLOS Pathogens: The fungal pathogen Magnaporthe oryzae suppresses innate immunity by modulating a host potassium channel (2018)

PLOS Pathogens: The fungal pathogen Magnaporthe oryzae suppresses innate immunity by modulating a host potassium channel (2018) | Plants and Microbes | Scoop.it

Potassium (K+) is required by plants for growth and development, and also contributes to immunity against pathogens. However, it has not been established whether pathogens modulate host K+ signaling pathways to enhance virulence and subvert host immunity. Here, we show that the effector protein AvrPiz-t from the rice blast pathogen Magnaporthe oryzaetargets a K+ channel to subvert plant immunity. AvrPiz-t interacts with the rice plasma-membrane-localized K+ channel protein OsAKT1 and specifically suppresses the OsAKT1-mediated K+ currents. Genetic and phenotypic analyses show that loss of OsAKT1 leads to decreased K+ content and reduced resistance against M. oryzae. Strikingly, AvrPiz-t interferes with the association of OsAKT1 with its upstream regulator, the cytoplasmic kinase OsCIPK23, which also plays a positive role in K+ absorption and resistance to M. oryzae. Furthermore, we show a direct correlation between blast disease resistance and external K+ status in rice plants. Together, our data present a novel mechanism by which a pathogen suppresses plant host immunity by modulating a host K+ channel.

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#RFBellagio Twitter Archive: Building resilience against crop diseases: A global surveillance system, February 2018

The conference on “Building resilience against crop diseases: A global surveillance system” is supported by the Rockefeller Foundation and will be held Feb. 12-16, 2018, at The Bellagio Center in Lake Como, Italy. Simone Staiger, Head of Knowledge Management and Learning at CIAT, is facilitating the meeting.

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Molecular Plant Pathology: Cassava brown streak disease: historical timeline, current knowledge and future prospects (2017)

Molecular Plant Pathology: Cassava brown streak disease: historical timeline, current knowledge and future prospects (2017) | Plants and Microbes | Scoop.it

Cassava is the second most important staple food crop in terms of per capita calories consumed in Africa and holds potential for climate change adaptation. Unfortunately, productivity in East and Central Africa is severely constrained by two viral diseases: cassava mosaic disease (CMD) and cassava brown streak disease (CBSD). CBSD was first reported in 1936 from northeast Tanzania. For approximately 70 years, CBSD was restricted to coastal East Africa and so had a relatively low impact on food security compared with CMD. However, at the turn of the 21st century, CBSD re-emerged further inland, in areas around Lake Victoria, and it has since spread through many East and Central African countries, causing high yield losses and jeopardizing the food security of subsistence farmers. This recent re-emergence has attracted intense scientific interest, with studies shedding light on CBSD viral epidemiology, sequence diversity, host interactions and potential sources of resistance within the cassava genome. This review reflects on 80 years of CBSD research history (1936–2016) with a timeline of key events. We provide insights into current CBSD knowledge, management efforts and future prospects for improved understanding needed to underpin effective control and mitigation of impacts on food security.

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Nature Genetics: Wheat receptor-kinase-like protein Stb6 controls gene-for-gene resistance to fungal pathogen Zymoseptoria tritici (2018)

Nature Genetics: Wheat receptor-kinase-like protein Stb6 controls gene-for-gene resistance to fungal pathogen Zymoseptoria tritici (2018) | Plants and Microbes | Scoop.it

Deployment of fast-evolving disease-resistance genes is one of the most successful strategies used by plants to fend off pathogens1,2. In gene-for-gene relationships, most cloned disease-resistance genes encode intracellular nucleotide-binding leucine-rich-repeat proteins (NLRs) recognizing pathogen-secreted isolate-specific avirulence (Avr) effectors delivered to the host cytoplasm3,4. This process often triggers a localized hypersensitive response, which halts further disease development5. Here we report the map-based cloning of the wheat Stb6gene and demonstrate that it encodes a conserved wall-associated receptor kinase (WAK)-like protein, which detects the presence of a matching apoplastic effector6,7,8 and confers pathogen resistance without a hypersensitive response9. This report demonstrates gene-for-gene disease resistance controlled by this class of proteins in plants. Moreover, Stb6 is, to our knowledge, the first cloned gene specifying resistance to Zymoseptoria tritici, an important foliar fungal pathogen affecting wheat and causing economically damaging septoria tritici blotch (STB) disease10,11,12.

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Persoonia: Phytophthora betacei, a new species on Solanum betaceum in Colombia (2018)

Persoonia: Phytophthora betacei, a new species on Solanum betaceum in Colombia (2018) | Plants and Microbes | Scoop.it

Over the past few years, symptoms akin to late blight disease have been reported on a variety of crop plants in South America. Despite the economic importance of these crops, the causal agents of the diseases belonging to the genus Phytophthora have not been completely characterized. In this study, a new Phytophthora species was described in Colombia from tree tomato (Solanum betaceum), a semi-domesticated fruit grown in northern South America. Comprehensive phylogenetic, morphological, population genetic analyses, and infection assays to characterize this new species, were conducted. All data support the description of the new species, Phytophthora betacei sp. nov. Phylogenetic analyses suggest that this new species belongs to clade 1c of the genus Phytophthora and is a close relative of the potato late blight pathogen, P. infestans. Furthermore, it appeared as the sister group of the P. andina strains collected from wild Solanaceae (clonal lineage EC-2). Analyses of morphological and physiological characters as well as host specificity showed high support for the differentiation of these species. Based on these results, a complete description of the new species is provided and the species boundaries within Phytophthora clade 1c in northern South America are discussed.

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Nature: An extracellular network of Arabidopsis leucine-rich repeat receptor kinases (2018)

Nature: An extracellular network of Arabidopsis leucine-rich repeat receptor kinases (2018) | Plants and Microbes | Scoop.it

The cells of multicellular organisms receive extracellular signals using surface receptors. The extracellular domains (ECDs) of cell surface receptors function as interaction platforms, and as regulatory modules of receptor activation1,2. Understanding how interactions between ECDs produce signal-competent receptor complexes is challenging because of their low biochemical tractability3,4. In plants, the discovery of ECD interactions is complicated by the massive expansion of receptor families, which creates tremendous potential for changeover in receptor interactions5. The largest of these families in Arabidopsis thaliana consists of 225 evolutionarily related leucine-rich repeat receptor kinases (LRR-RKs)5, which function in the sensing of microorganisms, cell expansion, stomata development and stem-cell maintenance6,7,8,9. Although the principles that govern LRR-RK signalling activation are emerging1,10, the systems-level organization of this family of proteins is unknown. Here, to address this, we investigated 40,000 potential ECD interactions using a sensitized high-throughput interaction assay3, and produced an LRR-based cell surface interaction network (CSILRR) that consists of 567 interactions. To demonstrate the power of CSILRR for detecting biologically relevant interactions, we predicted and validated the functions of uncharacterized LRR-RKs in plant growth and immunity. In addition, we show that CSILRR operates as a unified regulatory network in which the LRR-RKs most crucial for its overall structure are required to prevent the aberrant signalling of receptors that are several network-steps away. Thus, plants have evolved LRR-RK networks to process extracellular signals into carefully balanced responses.

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Communications Biology: Potential for re-emergence of wheat stem rust in the United Kingdom (2018)

Communications Biology: Potential for re-emergence of wheat stem rust in the United Kingdom (2018) | Plants and Microbes | Scoop.it

Wheat stem rust, a devastating disease of wheat and barley caused by the fungal pathogen Puccinia graminis f. sp. tritici, was largely eradicated in Western Europe during the mid-to-late twentieth century. However, isolated outbreaks have occurred in recent years. Here we investigate whether a lack of resistance in modern European varieties, increased presence of its alternate host barberry and changes in climatic conditions could be facilitating its resurgence. We report the first wheat stem rust occurrence in the United Kingdom in nearly 60 years, with only 20% of UK wheat varieties resistant to this strain. Climate changes over the past 25 years also suggest increasingly conducive conditions for infection. Furthermore, we document the first occurrence in decades of P. graminis on barberry in the UK . Our data illustrate that wheat stem rust does occur in the UK and, when climatic conditions are conducive, could severely harm wheat and barley production.

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Reuters: Scientists fear resurgence of devastating wheat disease in Britain and Europe (2018)

Reuters: Scientists fear resurgence of devastating wheat disease in Britain and Europe (2018) | Plants and Microbes | Scoop.it

A devastating disease that attacks barley and wheat - the world's most widely grown crop - could re-emerge in Britain, scientists said on Thursday.

 

Over 80 percent of 57 wheat varieties tested in Britain are susceptible to the strain of stem rust that was discovered in an infected plant in Suffolk in 2013, the first time the disease has reappeared since 1955, they said.

 

The same strain battered wheat crops in Ethiopia, and caused smaller outbreaks in Sweden, Denmark and Germany in 2013, a study in the journal Communications Biology said.

 

These outbreaks, as well as the infection in Britain, are "a warning sign" to take immediate action, Diane Saunders, a plant pathologist at the UK-based John Innes Centre and lead author of the study, told the Thomson Reuters Foundation.

 

Stem rust can devastate wheat, the source of food and livelihoods for more than 1 billion people in developing countries, according to the United Nations' Food and Agriculture Organization (FAO).

 

It could wipe out 70 percent or more of the crop, turning a healthy looking crop, only weeks away from harvest, into a tangle of black stems and shrivelled grains, the agency said.

 

The risks posed by wheat rusts are growing, with modern versions of the fungus becoming ever more virulent, evolving to adapt to the earth's higher temperatures, the FAO said.

 

Breeding wheat varieties resistant to the disease is key to controlling it and this can take a long time, Saunders said.

 

"Even if we have a resistant wheat line today that we just developed, it would take 10 years to get them to market," she said in a phone interview.

 

"There's very little resistance within our wheat varieties and if we did have an outbreak today, it could be quite devastating."

 

In the meantime, barberry bushes - an alternate host for stem rust - should not be planted near arable lands to prevent them from facilitating sexual reproduction and the re-infection of cereal crops, said Saunders.

 

The study's authors said they discovered stem rust in a barberry bush "within a meter of a barley field" in 2017.

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Journal of Experimental Botany: Modulation of R-gene expression across environments (2016)

Journal of Experimental Botany: Modulation of R-gene expression across environments (2016) | Plants and Microbes | Scoop.it

Some environments are more conducive to pathogen growth than others, and, as a consequence, plants might be expected to invest more in resistance when pathogen growth is favored. Resistance (R-) genes in Arabidopsis thaliana have unusually extensive variation in basal expression when comparing the same R-gene among accessions collected from different environments. R-gene expression variation was characterized to explore whether R-gene expression is up-regulated in environments favoring pathogen proliferation and down-regulated when risks of infection are low; down-regulation would follow if costs of R-gene expression negatively impact plant fitness in the absence of disease. Quantitative reverse transcription-PCR was used to quantify the expression of 13 R-gene loci in plants grown in eight environmental conditions for each of 12 A. thaliana accessions, and large effects of the environment on R-gene expression were found. Surprisingly, almost every change in the environment--be it a change in biotic or abiotic conditions--led to an increase in R-gene expression, a response that was distinct from the average transcriptome response and from that of other stress response genes. These changes in expression are functional in that environmental change prior to infection affected levels of specific disease resistance to isolates of Pseudomonas syringae. In addition, there are strong latitudinal clines in basal R-gene expression and clines in R-gene expression plasticity correlated with drought and high temperatures. These results suggest that variation in R-gene expression across environments may be shaped by natural selection to reduce fitness costs of R-gene expression in permissive or predictable environments.

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Plant Cell & Environment: Jasmonic and salicylic acid response in the fern Azolla filiculoides and its cyanobiont (2018)

Plant Cell & Environment: Jasmonic and salicylic acid response in the fern Azolla filiculoides and its cyanobiont (2018) | Plants and Microbes | Scoop.it

Plants sense and respond to microbes utilizing a multilayered signalling cascade. In seed plants, the phytohormones jasmonic and salicylic acid (JA and SA) are key denominators of how plants respond to certain microbes. Their interplay is especially well-known for tipping the scales in plants' strategies of dealing with phytopathogens. In non-seed plant lineages, the interplay is less well understood, but current data indicates that it is intertwined to a lesser extent and the canonical JA/SA antagonism appears to be absent. Here, we used the water fern Azolla filiculoidesto gain insights into the fern's JA/SA signalling and the molecular communication with its unique nitrogen fixing cyanobiont Nostoc azollae, which the fern inherits both during sexual and vegetative reproduction. By mining large-scale sequencing data, we demonstrate that Azolla has the genetic potential to produce and sense JA and SA. Using quantitative RT-PCR on the identified biosynthesis and signalling marker genes, we show that Azolla is responsive to exogenously applied SA. Furthermore, exogenous SA application influenced the abundance and gene expression of Azolla's cyanobiont. Our data provide a framework for JA/SA signalling in ferns and suggest that these phytohormones might be involved in the water fern's communication with its vertically inherited cyanobiont.

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Molecular Biology and Evolution: Diversification of Plant NBS-LRR Defense Genes Directs the Evolution of MicroRNAs That Target Them (2016)

Molecular Biology and Evolution: Diversification of Plant  NBS-LRR  Defense Genes Directs the Evolution of MicroRNAs That Target Them (2016) | Plants and Microbes | Scoop.it

High expression of plant nucleotide binding site leucine-rich repeat (NBS-LRR) defense genes is often lethal to plant cells, a phenotype perhaps associated with fitness costs. Plants implement several mechanisms to control the transcript level of NBS-LRR defense genes. As negative transcriptional regulators, diverse miRNAs target NBS-LRRs in eudicots and gymnosperms. To understand the evolutionary benefits of this miRNA-NBS-LRR regulatory system, we investigated the NBS-LRRs of 70 land plants, coupling this analysis with extensive small RNA data. A tight association between the diversity of NBS-LRRs and miRNAs was found. The miRNAs typically target highly duplicated NBS-LRRs. In comparison, families of heterogeneous NBS-LRRs were rarely targeted by miRNAs in Poaceae and Brassicaceae genomes. We observed that duplicated NBS-LRRs from different gene families periodically gave birth to new miRNAs. Most of these newly emerged miRNAs target the same conserved, encoded protein motif of NBS-LRRs, consistent with a model of convergent evolution for these miRNAs. By assessing the interactions between miRNAs and NBS-LRRs, we found nucleotide diversity in the wobble position of the codons in the target site drives the diversification of miRNAs. Taken together, we propose a co-evolutionary model of plant NBS-LRRs and miRNAs hypothesizing how plants balance the benefits and costs of NBS-LRR defense genes.

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Jonathan Lapleau's curator insight, February 1, 6:04 AM
NLR are known to be defense gene since long time, and are very important to fight pests. Having a better knowledge about downstream and upstream signaling event is very important to enhance crop resistance to pests (thus increasing global food security).
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PLOS Pathogens: Tricked or trapped—Two decoy mechanisms in host–pathogen interactions (2018)

PLOS Pathogens: Tricked or trapped—Two decoy mechanisms in host–pathogen interactions (2018) | Plants and Microbes | Scoop.it

Antagonistic interactions between hosts and pathogens frequently result in arms races. The host attempts to recognise the pathogen and inhibit its growth and spread, whereas the pathogen tries to subvert recognition and suppress host responses. These antagonistic interactions drive the evolution of ‘decoys’ in both hosts and pathogens. In host–pathogen interactions, the term decoy describes molecules that mimic a component at the host–pathogen interface that is manipulated during infection. Decoys undergo the same manipulation as the component they mimic, but they serve the opposite role, either by preventing manipulation of the component they mimic or by triggering a molecular recognition event. At least three different types of decoy have been defined, described in detail below. However, these different decoy models cause confusion on how they function mechanistically. Here, we discuss the three different types of decoys with examples and classify them according to two distinct mechanisms.

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Tweet from David Cooke‏ @Llewelyn68: update on Phytophthora infestans in the UK (2018)

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Annual Reviews of Virology: Cassava Mosaic and Brown Streak Diseases: Current Perspectives and Beyond (2018)

Annual Reviews of Virology: Cassava Mosaic and Brown Streak Diseases: Current Perspectives and Beyond (2018) | Plants and Microbes | Scoop.it

Cassava is the fourth largest source of calories in the world but is subject to economically important yield losses due to viral diseases, including cassava brown streak disease and cassava mosaic disease. Cassava mosaic disease occurs in sub-Saharan Africa and the Asian subcontinent and is associated with nine begomovirus species, whereas cassava brown streak disease has to date been reported only in sub-Saharan Africa and is caused by two distinct ipomovirus species. We present an overview of key milestones and their significance in the understanding and characterization of these two major diseases as well as their associated viruses and whitefly vector. New biotechnologies offer a wide range of opportunities to reduce virus-associated yield losses in cassava for farmers and can additionally enable the exploitation of this valuable crop for industrial purposes. This review explores established and new technologies for genetic manipulation to achieve desired traits such as virus resistance.

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CGSpace: Defeating cassava witches’ broom: a cartoon guide for extension workers and farmers in South East Asia (2015)

CGSpace: Defeating cassava witches’ broom: a cartoon guide for extension workers and farmers in South East Asia (2015) | Plants and Microbes | Scoop.it
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Nature Genetics: Stress and sexual reproduction affect the dynamics of the wheat pathogen effector AvrStb6 and strobilurin resistance (2018)

Nature Genetics: Stress and sexual reproduction affect the dynamics of the wheat pathogen effector AvrStb6 and strobilurin resistance (2018) | Plants and Microbes | Scoop.it

Host resistance and fungicide treatments are cornerstones of plant-disease control. Here, we show that these treatments allow sex and modulate parenthood in the fungal wheat pathogen Zymoseptoria tritici. We demonstrate that the Z. tritici–wheat interaction complies with the gene-for-gene model by identifying the effector AvrStb6, which is recognized by the wheat resistance protein Stb6. Recognition triggers host resistance, thus implying removal of avirulent strains from pathogen populations. However, Z. tritici crosses on wheat show that sex occurs even with an avirulent parent, and avirulence alleles are thereby retained in subsequent populations. Crossing fungicide-sensitive and fungicide-resistant isolates under fungicide pressure results in a rapid increase in resistance-allele frequency. Isolates under selection always act as male donors, and thus disease control modulates parenthood. Modeling these observations for agricultural and natural environments reveals extended durability of host resistance and rapid emergence of fungicide resistance. Therefore, fungal sex has major implications for disease control.

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bioRxiv: A small subset of NLR genes drives local adaptation to pathogens in wild tomato (2017)

bioRxiv: A small subset of NLR genes drives local adaptation to pathogens in wild tomato (2017) | Plants and Microbes | Scoop.it

In plants, defence-associated genes including the NLR gene family are under constant evolutionary pressure to adapt to pathogens. It is still unknown how many NLRs contribute to adaptation, and if the involved loci vary within a species across habitats. We use a three-pronged approach to reveal and quantify selection signatures at over 90 NLR genes over 14 populations of Solanum chilense a wild tomato species endemic to Peru and Chile found in different habitats. First, we generated a de novo genome of S. chilense. Second, by whole genome resequencing of three geographically distant individuals we infer the species past demographic history of habitat colonisation. Finally, using targeted resequencing we show that a small subset of NLRs, 7%, show signs of positive or balancing selection. We demonstrate that 13 NLRs change direction of selection during the colonisation of new habitats and form a mosaic pattern of adaptation to pathogens. We estimate that the turn over time of selection (birth-and-death rate) on NLRs is 18,000 years. Finally, our work identifies new NLRs under strong selective pressure between habitats, thus providing novel opportunities for R-gene identification.

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Sci Dev Net: Wheat plague spreading through Yemen (2018)

Sci Dev Net: Wheat plague spreading through Yemen (2018) | Plants and Microbes | Scoop.it

New strains of stem rust threaten huge cultivation areas of the essential crop in Africa, Asia and Europe.

 

  • Spread of ‘black rust’ through Yemen a risk for wheat crops in Africa, Asia, Europe
  • North African country is key to tracking, containing strains of the fungus
  • FAO and local authorities intensify control with coordination, training
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Estimating virus effective population size and selection without neutral markers

Estimating virus effective population size and selection without neutral markers | Plants and Microbes | Scoop.it

By combining high-throughput sequencing (HTS) with experimental evolution, we can observe the within-host dynamics of pathogen variants of biomedical or ecological interest. We studied the evolutionary dynamics of five variants of Potato virus Y (PVY) in 15 doubled-haploid lines of pepper. All plants were inoculated with the same mixture of virus variants and variant frequencies were determined by HTS in eight plants of each pepper line at each of six sampling dates. We developed a method for estimating the intensities of selection and genetic drift in a multi-allelic Wright-Fisher model, applicable whether these forces are strong or weak, and in the absence of neutral markers. This method requires variant frequency determination at several time points, in independent hosts. The parameters are the selection coefficients for each PVY variant and four effective population sizes Ne at different time-points of the experiment. Numerical simulations of asexual haploid Wright-Fisher populations subjected to contrasting genetic drift (Ne ∈ [10, 2000]) and selection (|s| ∈ [0, 0.15]) regimes were used to validate the method proposed. The experiment in closely related pepper host genotypes revealed that viruses experienced a considerable diversity of selection and genetic drift regimes. The resulting variant dynamics were accurately described by Wright-Fisher models. The fitness ranks of the variants were almost identical between host genotypes. By contrast, the dynamics of Ne were highly variable, although a bottleneck was often identified during the systemic movement of the virus. We demonstrated that, for a fixed initial PVY population, virus effective population size is a heritable trait in plants. These findings pave the way for the breeding of plant varieties exposing viruses to stronger genetic drift, thereby slowing virus adaptation.

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Wikimedia Commons: Movie - Hyphal growth of phagocytosed Fusarium-oxysporum causes cell lysis of murine macrophages (2014)

Wikimedia Commons: Movie - Hyphal growth of phagocytosed Fusarium-oxysporum causes cell lysis of murine macrophages (2014) | Plants and Microbes | Scoop.it

Schaefer et al. 2004.

 

The soil-borne plant pathogen Fusarium oxysporum causes life-threatening invasive fusariosis in immunocompromised individuals. The mechanism of infection in mammalian hosts is largely unknown. In the present study we show that the symptoms of disseminated fusariosis caused by F. oxysporum in immunosuppressed mice are remarkably similar to those reported in humans. Distinct fungal structures were observed inside the host, depending on the infected organ. Invasive hyphae developed in the heart and kidney, causing massive colonization of the organs. By contrast, chlamydospore-like survival structures were found in lung, spleen and liver. Systemically infected mice also developed skin and eye infections, as well as thrombosis and necrosis in the tail. We further show that F. oxysporum can disseminate and persist in the organs of immunocompetent animals, and that these latent infections can lead to lethal systemic fusariosis if the host is later subjected to immunosuppressive treatment.

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Plant Cell: Defended to the Nines: 25 years of Resistance Gene Cloning Identifies Nine Mechanisms for R Protein Function (2018)

Plant Cell: Defended to the Nines: 25 years of Resistance Gene Cloning Identifies Nine Mechanisms for R Protein Function (2018) | Plants and Microbes | Scoop.it

Plants display extensive genetic variation at resistance (R) gene loci for resistance to a variety of pathogens. The first R gene, Hm1, was cloned over 25 years ago, and many different R genes have since been identified and isolated. The encoded proteins have provided clues to diverse molecular mechanisms underlying immunity. The majority encode either cell-surface or intracellular receptors, and we present here a meta- analysis of 314 cloned R genes. We distinguish nine molecular mechanisms by which R proteins can elevate or trigger disease resistance. These mechanisms include direct (1) and indirect (2) perception of pathogen-derived molecules on the cell surface by receptor-like proteins and -kinases; intracellular detection of pathogen-derived molecules by nucleotide-binding, leucine-rich repeat receptors (NLRs), either directly (3), indirectly (4) or through integrated domains (5); perception of Transcription Activator-like (TAL) effectors through activation of Executor genes (6); and loss-of-susceptibility, either active (7), passive (8), or by host reprogramming (9). Although the molecular mechanisms underlying the function of R genes are only understood for a small proportion of these, a clearer understanding of mechanisms is emerging and will be crucial for rational engineering and deployment of novel R genes.

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Trends in Microbiology: Rise of a Cereal Killer: The Biology of Magnaporthe oryzae Biotrophic Growth (2018)

Trends in Microbiology: Rise of a Cereal Killer: The Biology of Magnaporthe oryzae Biotrophic Growth (2018) | Plants and Microbes | Scoop.it

The rice blast fungus, Magnaporthe oryzae, causes one of the most destructive diseases of cultivated rice in the world. Infections caused by this recalcitrant pathogen lead to the annual destruction of approximately 10–30% of the rice harvested globally. The fungus undergoes extensive developmental changes to be able to break into plant cells, build elaborate infection structures, and proliferate inside host cells without causing visible disease symptoms. From a molecular standpoint, we are still in the infancy of understanding how M. oryzae manipulates the host during this complex multifaceted infection. Here, we describe recent advances in our understanding of the cell biology of M. oryzae biotrophic interaction and key molecular factors required for the disease establishment in rice cells.

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